The present invention relates to the combined utilization of optical photonic data network switch fabrics (OSF)7 and data packet-based electrical switch fabric networks (ESF)being more particularly concerned with eliminating some of the operational inefficiencies in current data networks wherein multiple and separate control mechanisms and protocols are used for operating ESF and OSF nodesxe2x80x94the invention combining packet-based and photonic networks by providing a hardware architecture with appropriate software algorithms that transform current ESF and OSF network designs and operation from multiple control layers to a one-layer common software control plane that can be represented as an integrated node solution. This novel solution also enables financial benefits through more efficient use of optical path capability for network operators through the use of this invention.
Present-day electrical data networks are divided into layers composed of homogenous devices, such as ATM switches for ATM networks, Frame Relay switches for Frame Relay networks, and various other electrical data packet switching technology; and separate photonic or optical crossconnects are also used for optical light-only networks. These OSF and ESF networks operate independently, and are managed independently.
Current operation employs shortest path first (SPF) algorithms to determine best ways to send data traffic through a network. SPF algorithms are also referred to as Dijkstra algorithms. For the purpose of computation, the data networks are composed of computer nodes and interface links such as a fiberoptic link that connects computer nodes to one another directly, or it may be a fiber optic link that connects to a photonic network. The photonic network (OSF), however, is currently completely transparent to or unaware of the control algorithms (i.e. SPF) of the electrical data network (ESF).
Fundamental to the algorithms of the electrical data network, however, is the notion of xe2x80x9clink.xe2x80x9d The purpose of SPF control algorithms is to minimize cost; for example, the number of hops or links that data must traverse from ingress node to egress node. Metrics other than hops may also be used. Link information, however, is indeed the essence of information that is transmitted as control information between nodes in a computer network. SPF algorithms (OSPF, ISIS, PNNI, etc) all operate in a similar manner even though details vary. SPF algorithms were first implemented on the ARPANET in the late 1970""s as described, for example, in McQuillan, et. al. xe2x80x9cThe New Routing Algorithm for the Arpanet,xe2x80x9d IEEE Transactions on Communications, May 1980. The basic function of these algorithms is to distribute on a hop-by-hop manner a summarization of the status of each link that a device contains. The total collection of all the summarizations from each node in the network is collected in a xe2x80x9cLink State Database.xe2x80x9d The SPF algorithm is run on this database, resulting in minimum distance information from the node doing the calculation, to every other node on the network. In fact, each node in the network does this calculation.
More recently, the concept of type/length/value (TLV) was introduced into the standards, such as OSPF-TE to enhance the capability of SPF-type algorithms, as described, for example, in IETF-draft-ietf-ccamp-ospf-gmpls-extensions-00.txt, OSPF Extensions in Support of Generalized MPLS, work in progress, September 2001. TLVs are appended to standard messages in these protocols to convey information that may be pertinent for some enhanced capability of the network such as Traffic Engineering. These TLVs, for example, may carry information containing maximum and actually used bandwidth on a link. With this information, the SPF algorithms may be modified as necessary to take bandwidth as well as other conventional costs into consideration, including distance, when making a traffic forwarding decision. The underlying SPF infrastructure is not changed, but it is enhanced.
Like any algorithm, there are certain key behavioral concepts that exemplify the working of SPF algorithms. For example, traffic would not enter and exit from the same node and link combination. This would produce non-optimal behavior in so far as SPF is concerned.
The majority of these procedures are defined, or are in the process of being defined, in the Internet Engineering Task Force (IETF), as above referenced, a standards body dedicated to the Internet protocols. Some of the current efforts are works in progress such as IETF-draft-katz-yeung-ospf-traffic-01.txt, Traffic Engineering Extensions to OSPF, work in progress, October 1999, IETF-draft, draft-ietf-mpls-rsvp-lsp-tunnel-05.txt, RSVP-TE: Extensions to RSVP for LSP Tunnels, work in progress, February 2000, and the above citation of September 2001.
Where such electrical data communication networks are used together with optical photonic light communication network links, for example, each type of networkxe2x80x94electrical and opticalxe2x80x94has its own and separate and homogeneous common control protocol and layers, as before mentioned. When the boundaries between ESF and OSF come together, however, still a third set or layer of common protocols is currently required.
The underlying intention of the present invention, on the other hand, is no longer to treat the ESF and OSF as separate devices but, rather, as one integrated node, and with current control algorithms modified so that such node appears to operate as one device, not as two separate independent devicesxe2x80x94integrating OSF and ESF switching capacities so that they are managed as a single xe2x80x9cboxxe2x80x9d or device.
A primary object of the invention, accordingly, is to provide a new and improved method of and system-operating architectural enhancement for combining optical (photonic) and data (packet-based) devices as single, integrated nodes using a common software control plane or layer, and thus obviating the multiple layer separate control limitations before described.
A further object is to provide such a novel technique whereby increased utilization of data flow can be provided along an under-utilized, but, available, data flow capability of an optical path, by determining such under-utilization and inserting supplemental data into such path.
Still an additional object is to provide such supplemental data in this under-utilized optical path from either electrical datapackets from an electrical switch fabric or from a further optical path in the optical switch fabric.
Other and further objects will be explained hereinafter and are more fully delineated in the appended claims.
In summary, however, from one of its more generic aspects, the invention embraces in a combined optical data-electrical data switch fabric system, a method of more fully utilizing the available data flow capacity of optical paths through the optical switch fabric, that comprises, flowing photonic data packets along a predetermined optical path in the optical switch fabric; flowing other data packets along a separate data flow path; determining when the predetermined optical path is under-utilized in its available data flow capability and the desirability of inserting in that predetermined optical path additional data from the separate data flow path; diverting the photonic data packet flow along said predetermined path into the electrical switch fabric and converting the same into electrical data packets; joining the converted electrical data packets with said other data packets also presented in electrical data packet form; converting the joined electrical data packets into photonic data packet flow; and sending the converted joined photonic data packets along said predetermined optical path of the optical switch fabric.
More specifically, the invention combines an electrical switch fabric (ESF) capability and an optical switch fabric (OSF) capability connected by various hardware elements that are referred to as bridge cards, all managed by a single piece of software referred to as the common control plane. The algorithms that are used to represent the device in the network, however, do not represent the bridge cards as xe2x80x9clinksxe2x80x9d in the network, but rather they are used as xe2x80x9cconversion elements.xe2x80x9d This allows the device to be viewed as a single entity in the network rather than as two distinct elements. By so combining the two different switching elements in a single device allows cost savings and the use of a single control computer for both elements that simplifies the control algorithms that are necessary to manage both the optical and electrical elements.
In the prior art, traffic in an all-optical environment of an OSF would flow from optical port to optical port without inspections of the contents of the traffic. This is called the before-mentioned photonic switching. Similarly, with ESF nodes, traffic would flow from electrical port to electrical port, though this traffic is inspected. Furthermore, traffic could enter the photonic network from an electrical port by use of a conversion element and vice versa. These traffic flows are fairly standard applications even with the present invention.
The invention, however, provides new and important other traffic patterns. When an optical flow is terminated at the ESF via one of the conversion elements, instead of going out an electrical port, the traffic may now be aggregated with other electrical traffic from the electrical port and sent back into the optical network to use available data flow capability of the optical path (s). This not only increases the utilization of the network, but it decreases operational costs and improves manageability as is discussed in greater detail hereinafter.
Preferred and best mode embodiments are also explained.